Field of the Invention
The present invention relates to improvements made to time-division multiplex switching networks and, more particularly, to switching networks of this type in which the buffer store is an associative type store addressable by its contents and constructed using coupled charge devices (CCD).
Description of the Prior Art
U.S. Pat. No. 3,971,892 includes a description of a time-division multiplex switching network comprising an input stage having plurality of incoming multiplex highways and a supermultiplexer converting the said incoming multiplex highways into one incoming supermultiplex highway; an output stage having outgoing supermultiplex highway and a superdemultiplexer converting the said outgoing supermultiplex highway into a plurality of outgoing multiplex highways; a buffer store having a write in input connected to the incoming supermultiplex highway and a read out output connected to the outgoing supermultiplex highway; and means for sequentially writing, in data storage locations of the buffer store, the words present in the time-slots of the incoming supermultiplex highway. The said buffer store is a circulating store addressable by its contents. The buffer store includes random address store locations associated with the said data store locations and a fixed address store giving the addresses of the component time-slots of the outgoing supermultiplex highway. Plural comparator means, each associated with a data store location, and a random address store location compare the random addresses written in the address store locations with the fixed addresses of the component time-slots of the outgoing supermultiplex highway to control read out of the word associated with a given random address when there is identity between the said given random address and a fixed address.
Assuming that there are N multiplex highways in a supermultiplex highway and 32 time-slots in each multiplex highway, the address (j-i) modulo 32N is written in the random address store location associated with the data store location containing the word in time-slot of address i in the incoming supermultiplex highway and the circulating store advances stepwise. When random address (j-i) is equal to fixed address (j-i) assigned to a given step of the circulating store, the word is read out and transferred into time-slot of address j in the outgoing supermultiplex highway.